// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package qunar.tc.decompiler.util;

import java.io.*;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

public class InterpreterUtil {
    public static final boolean IS_WINDOWS = System.getProperty("os.name", "").startsWith("Windows");

    public static final int[] EMPTY_INT_ARRAY = new int[0];

    private static final int BUFFER_SIZE = 16 * 1024;

    public static void copyFile(File source, File target) throws IOException {
        try (FileInputStream in = new FileInputStream(source); FileOutputStream out = new FileOutputStream(target)) {
            copyStream(in, out);
        }
    }

    public static void copyStream(InputStream in, OutputStream out) throws IOException {
        byte[] buffer = new byte[BUFFER_SIZE];
        int len;
        while ((len = in.read(buffer)) >= 0) {
            out.write(buffer, 0, len);
        }
    }

    public static byte[] getBytes(ZipFile archive, ZipEntry entry) throws IOException {
        try (InputStream stream = archive.getInputStream(entry)) {
            return readBytes(stream, (int) entry.getSize());
        }
    }

    public static byte[] getBytes(File file) throws IOException {
        try (FileInputStream stream = new FileInputStream(file)) {
            return readBytes(stream, (int) file.length());
        }
    }

    public static byte[] readBytes(InputStream stream, int length) throws IOException {
        byte[] bytes = new byte[length];

        int n = 0, off = 0;
        while (n < length) {
            int count = stream.read(bytes, off + n, length - n);
            if (count < 0) {
                throw new IOException("premature end of stream");
            }
            n += count;
        }

        return bytes;
    }

    public static void discardBytes(InputStream stream, int length) throws IOException {
        if (stream.skip(length) != length) {
            throw new IOException("premature end of stream");
        }
    }

    public static boolean equalSets(Collection<?> c1, Collection<?> c2) {
        if (c1 == null) {
            return c2 == null;
        } else if (c2 == null) {
            return false;
        }

        if (c1.size() != c2.size()) {
            return false;
        }

        HashSet<Object> set = new HashSet<>(c1);
        set.removeAll(c2);
        return (set.size() == 0);
    }

    public static boolean equalObjects(Object first, Object second) {
        return first == null ? second == null : first.equals(second);
    }

    public static boolean equalLists(List<?> first, List<?> second) {
        if (first == null) {
            return second == null;
        } else if (second == null) {
            return false;
        }

        if (first.size() == second.size()) {
            for (int i = 0; i < first.size(); i++) {
                if (!equalObjects(first.get(i), second.get(i))) {
                    return false;
                }
            }
            return true;
        }

        return false;
    }

    public static String makeUniqueKey(String name, String descriptor) {
        return name + ' ' + descriptor;
    }

    public static String makeUniqueKey(String name, String descriptor1, String descriptor2) {
        return name + ' ' + descriptor1 + ' ' + descriptor2;
    }
}